(1) Field of the Invention
The invention is related to an obstacle information system of a helicopter with the features of the preamble of claim 1 and to a method of operating an obstacle information system with the features of claim 14.
(2) Description of Related Art
A proximity sensor of an aircraft detecting an obstacle or several obstacles, such as buildings, towers, power lines, terrain etc. in a certain direction around the aircraft and within a critical distance with respect to the aircraft, essentially provides a warning or an alert to the pilot. The more critical the obstacles are for the aircraft, the more visible and flashy the warning/alert should be. According to a general assumption there are two zones around the aircraft: a warning zone and an alert zone. If there are any obstacles within one of these zones, a warning or alert should be submitted to the pilot—this warning or alert should be given as long as the aircraft is within the respective zones. Currently known warning instruments don't satisfy all the requirements concerning the situation awareness of the pilots.
The document WO 2011/136707 A1 discloses an obstacle detection and information system of a helicopter arranged to be transmitting laser light and receiving reflected laser light from obstacles for detecting and informing the pilot of a helicopter of obstacles in proximity of the helicopter. The system comprising an obstacle detection sensor unit, being arranged to be mounted on a rotor head of a helicopter such that said obstacle detection sensor unit is arranged to rotate with said rotor head when mounted, further comprising an information unit. The transmitted laser light is arranged to cover a sector volume around a rotor head axis, having a coverage defined as a radial extension (R1, R2) in a sector plane around said rotor head axis and an angular extension perpendicular to said sector plane, and wherein communication means are arranged for communication between said sensor unit and said information unit.
The document DE 10 2006 053 354 B4 discloses a panoramic obstacle detection and warning system comprising radar sensors and a display means for the warnings. Several alternatives are proposed for said detection and warning system: 1. Indication of a horizontal obstacle by colouring a respective sector of a round instrument with red or amber colours; 2. Indication of an obstacle by circles or ellipses on a 2D navigation or mission display in range and direction relative to the helicopter symbol; and 3. Indication of the risk levels and spatial hazard picture by coloured, range dependent bars in a joint display. Disadvantages remain for any of these alternatives: Ad 1: There are only two levels of warnings: amber (warning) and red (alert). The pilot has no idea about how the helicopter is moving inside the different zones—reducing or increasing the distance to the obstacle; Ad 2: The visibility of the warning is only increased by the change of the colours: from amber to red. There is no intensification of the visual representation foreseen; and Ad 3: This representation of the warning/alert function might be considered to be too abstract for the pilot since there are only four different directions according to the 90° sectors represented. Any interpolation is left to the interpretation of the pilot.
The document U.S. Pat. No. 8,249,762 B1 discloses a device for monitoring obstructions for an aircraft including data storage, an anti-collision device and viewing devices, wherein the monitoring device comprises a detector to detect in real-time obstructions, of terrain type and of human constructions type, in a close environment of the aircraft in a flight situation, a sensor to identify the obstructions at risk calculating identification parameters, a circuit to calculate criticality of the obstructions, a display to display both the obstructions with the identification and criticality parameters of the obstructions, and a generator of alerts to describe the situation according to a combination of the identification and criticality parameters.
The document WO 2008/116456 A1 discloses an all-around identification of obstacles within the movement area of a helicopter using radar, laser and/or ultrasonic sensors. The ranges of the sensors that are used are selected in accordance with the movement area and the installation locations of the sensors on the helicopter, predetermined scanning movements related to the scanning area are communicated to the sensors and all measuring signals of the sensors received by means of reflection and their individual positions are fed to a common database after an individual signal evaluation that is ordered according to the scanning area, said signals being respectively referenced in terms of distance and direction with the position of the helicopter and being fed in the form of a received reflective field in order to combine all reflective fields and compare them with patterns stored in the database. The complete layout of the movement area that is to be monitored is determined using a subsequent algorithmic evaluation and is displayed as a complete image in the cockpit of the helicopter.
The document U.S. 2012/029738 A1 discloses an aircraft capable of hovering by having at least one sensor, which has a plane sweep region and is designed to acquire, when the aircraft is maneuvering, values of respective distances between first points on an obstacle within the plane sweep region, and a second point on the aircraft; and a control unit designed to generate an alarm signal when at least one of the first points lies within a safety region containing the second point on the aircraft.